Concentration Definition and 550 Threads

Homework Statement You have 200 mL of perfluorooctanesulfonic acid with a concentration of 10 mg/L. If the PFOS is completely mineralised in solution what is the expected concentration of fluoride in solution? The experimentally determined fluoride concentration is 5.6 mg/L Homework Equations...

Homework Statement For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00L container. A(g) + 2B(g) --> C(g) At equilibrium, the concentration of A is 0.246 mol/L. What is the concentration of B at equilibrium? Homework Equations for aA+bB-->cC, K = [C]^c/([A]^a[...

What is the PH of 20%, 40% and 60% concentration of the citric acid solution?

Homework Statement The hydroxide ion concentration in an aques H2CO3 solution is 4X10^{-4}M at 25°C OH- ion concentration in the solution is Homework Equations Ph=log(H+ or OH-) [/B]The Attempt at a Solution I calculated the PH of H+ in the solution which came to be 4.3979.Considering...

Hi! Here's a tricky thermodynamics problem, I hope you can help with it. 1. Homework Statement The boundary between two different materials can be divided into two different kind of phases: bulk phases and surface phases. For example, let's consider a boundary between water and air. We can...

Hi I'm looking for some help that I think is easy but just can't get my head round. So I need to make a solution with a concentration of 10% bleach to remove DNA contamination from equipment. So if I had 100ml of water I'd need 10ml of bleach to make a 10% solution. But it is the active chlorine...

Hi All, Is it possible to know the concentration of a solute when you have only its composition? I.e : the solute contains 1 molecule of water for each k+

1. In my materials science's exam, I had the following question: What would be the maximum force F to cause failure in a block that has been drilled at two place? See following drawing: (Lame paint skills, I know..) 2. Homework Equations 1) D/W 2) σ = F/S The Attempt at a Solution 1)First...

Homework Statement For silicon at T=300K with donor density ND=2×109cm−3, acceptor density NA=0 and ni=8.2×109cm−3, calculate the equilibrium electron and hole concentration Homework Equations n_0=\frac{N_D-N_A}{2}+\sqrt{\frac{N_D-N_A}{2}^2+n_i^2} p_o=\frac{n_i^2}{n_0} The Attempt at a...

Hi All, (Just for information and understanding), If we have a concentration cell experiment like the image uploaded, in a concentration cell, the solutes are supposed to be of the same kind, iI.e. CuCl2 (?). I suppose it is possible to add to the left vat a m quantity or volume of CuSO4 to...

Homework Statement Convert a number concentration of 15 X 10^12 molecule/cm3 into volume mixing ratio at: a) 1 atm pressure, and 20 C temperature. b) 500 mbar pressure, and 253 K temperature. Using the Ideal Gas Law, calculate: a) Loshmidt’s number (# of molecules/cm3 of air, at standard...

Homework Statement The ionization constant of ## {(C_2 H_5)}_3 {N}## is 6.4 x 10^(-5). Calculate degree of dissociation in its 0.1 M solution when it is mixed with 0.01 M NaOH solution. 2. The attempt at a solution the compound gives ##{(C_2 H_5)}_3 {NH+}## and ##OH-##. C is initial...

Homework Statement Place 20.0 g NaOH(s) in a flask and dilute to 1.00 L with water. Place 20.0 g NaOH(s) in a flask and add 1.00 L of water. How exactly do these two statements differ? Wouldn't adding 1.00L of water to 20.0g of NaOH dilute it anyways? Homework Equations none? The Attempt...

Homework Statement Calculate the pH of the following solutions: (caution: these are hydrolysis reactions) a. an 0.30 M solution of NaF Homework Equations I think by hydrolysis reactions they mean that each of the given compounds is combined with $H_2O$. Then for a) NaF + HF <-->...

Homework Statement Calculate the pH of a 0.20 M solution of iodic acid ##(HIO_3)##. ##K_a## for iodic acid is 0.17 Homework Equations ##K_a = \frac{[H^+][IO_3^-]}{[HIO_3]}## The Attempt at a Solution ##[HIO_3] = 0.20## M. The concentration of ##[H^+]## and ##[IO_3^-]## should be the same...

Homework Statement Suppose that we have a system consisting of two interconnected tanks, each containing a brine solution. Tank A contains x(t) pounds of salt in 200 gallons of brine, and tank B contains y(t) pounds of salt in 300 gallons of brine. The mixture in each tank is kept uniform by...

I am a math major with a concentration in Pre-Medicine and I am setting up my program for next year. I was wondering if taking Bio w/ a lab, Chem w/ a lab, Calc II and Linear algebra is just an unrealistic idea.

Homework Statement This isn't homework, rather it's regular work. I have a >97% solution of 1-thioglycerol, the density of which is 1.25 g/mL. I am trying to get a 1.5 x 10-4 M solution at the end, and I suspect the instructions I have been given are incorrect. Molar mass = 108.16 Homework...

Hi, I had been reading about the fatigue stress concentration factor (Kf) which is reduced compared to the geometric stress concentration factor (Kt). The reduction in turn dpends upon the material's sensitivity to notches...

Hi, I recently have been trying to look into whether or not white noise works as a means to block out external sounds so i can concentrate. However, I want to know whether it actually impairs studying and reading. I do not care if it has no benefit, as long as it has no negative effects. I am...

Hi everyone, I am working on a second bachelor's degree in Computer Science, and am hoping to enter a Phd program in fall of 2019. Recently, I have taken an interest in Chaos Theory and was wondering if it is possible to do research in the field in the Computer Science department, or if it is...

When I set the differential equation (mass transfer) to find the the concentration profile of the i-spice I also need boundary condition to solve it. Inside the pipe (along its axis of symmetry) the concentration has a maximum (first derivate has to be 0), while on the internal surface... should...

I'm very sorry for the lengthy post. I'm actually not sure as to how to deal with this as this is the first time I've been assigned to these kinds of problems; I need to be sure. Thanks in advance. So I have this large basin-like structure whose water naturally has K+ ions dissolved in it...

Homework Statement Find the concentrations of all ions in the solution at equilibrium after 0.213 L of 0.433 M aqueous Cu(NO3)2 solution is mixed with 0.213 L of 0.120 M KOH solution. Ksp for Cu(OH)2 is 1.1E-15. Homework Equations n=m/M [Cu][OH]^2 = Ksp .. ?The Attempt at a Solution ok so for...

Homework Statement Homework Equations M = n/1 L The Attempt at a Solution I was wondering if the answer is 6E. I'm not too sure about what the question is asking but i do know that the more moles there are, the more concetration of ions there will be. So, E seems like the answer since it...

Homework Statement I've looked up the intrinsic carrier concentration of silicon, and what I've got isn't close. The question says given there are ##2\times 10^{22}## electrons per cubic cm in silicon, and the bandgap is ##1.1##eV, what is the free electron concentration at room temperature...

Homework Statement What mass of aluminum nitrate should be dissolved in 225 ml of water to make a solute with a total nitrate concentration of 0.866 M ? Homework Equations M = n/L The Attempt at a Solution So, i keep getting the wrong answer. THe answer is suppose to be 13.8 g but i get a...

I haven't had a chemistry class in many years. Recently I saw an interesting article that used a solution of resveratrol (228.25 grams per mole) in dimethylsulfoxide (78.13 grams per mole). The concentration was listed as 5 uMol. If I had 10 grams of DMSO how much resveratrol would I add to...

I made liquid analyzing device based on beer lambert law. I am getting very accurate results when using rich colored liquids but when concentration of colored liquid is dropping beyond certain level I am getting non consistent results. Example: Mixing 2 liquids with concentration 10:1 or 30:1 I...

Hello everyone! So I made a study program and it's 10 hours studying per day. I will have it everyday till May. After 30 min of studying I take a 5 min break and after 2 hours, 15 min break. Is that sound bad? Plus, till now due to different factors I have studied around 4 hours per day. How...

Homework Statement What is the molality of 1M NH4OH dissolved in 70.092ml of water? What is the total mass of the solution? What is the total volume? What is the concentration percent? What is the molar concentration? 1M NH4OH = 35.046g density of water = 1g/ml density of NH4OH = 0.88 g/ml...

In our laboratory class we were required to calculate the stock (mM) and final (µM) concentrations for Glycerol. The tutor said my final calculations were incorrect and that I had made an error. He didn't have enough time show me where I went wrong. I have compared my results with another...

Hi Everyone, I was just learning about action potential generation via electrochemical gradients. I was just wondering, does anyone know whether a +1 unit of concentration gradient is stronger/weaker than a +1 unit of electrical gradient? For example: If side-A of a split chamber had a net...

We recently performed an experiment with the idea to find refractive index of medium (water) as a function of wavelength of light. We then added some sugar to see how the refractive index changes with concentration of sugar solution. We got the following graphs. Are the relationships actually...

< Mentor Note -- two threads merged and new user reminded not to multiple-post threads at the PF >[/color] i'm experimenting about refractive index and i can't figure out the relationship between concentration of the solution and Refractive index. What i found about this is that RI is...

Homework Statement The nitrate concentration in an aquifer is 20 ppm, and its volume is ten million liters. What mass of ammonia upon oxidation would have produced this mass of nitrate? [Hint: The moles of nitrogen in reactant and product are identical.] Homework Equations Possibly 1mg/L &...

I really hope someone can help. I have spent the last week several hours a day trying to get this answer via Google. I am doing research on the practical difference between a mace and axe in combat. Strangely enough there's almost nothing concerning the techniques of using a mace in period...

Homework Statement 10.00 cm3 of 1.00 mol dm–3 sulfuric acid is fully neutralized by 20.00 cm3 of 1.00 mol dm–3 of sodium hydroxide. What is the concentration, in mol dm–3, of sodium sulfate solution produced by the reaction? A 0.33 B 0.50 C 0.67 D 1.00 Correct answer = A Homework Equations...

Homework Statement The stress distribution along the section of a bar is shown below. From this distribution, find the approximate axial force P in kip. Homework Equations δavg=P/A A= (.6+.6)(.5) δavg=30ksi[/B]The Attempt at a Solution P=(30ksi)(.6in2)=18kip It says this answer is wrong...

1. The problem statement, "all variables and given/known data A solution of nitric acid, HNO3, of concentration 100 g dm-3, can be used to artificially age wood. A sample of nitric acid was tested by pipetting 10.00 cm3 of the acid into a 250 cm3 volumetric flask and filled up with deionised...

What would be the theoretical relationship between/ a formula for the salt concentration in distilled water and its electrical resistance?

My main goal is optics. I love it. I did an internship having to study and learn about optics and I've had my sights set on it sense then. It's also easier for me to learn. I've applied to graduate schools, but I need to know: Are there any advantages or disadvantages of going to an optics...

A lab mate and I are discussing how to properly interpret LCMS results and coming to different conclusions. We are taking a solid food sample and extracting it with 50:50 acetonitrile/water to determine the concentration of melamine in the food sample. Standard solutions were made that range...

What happens to one of the components when it is at VERY low concentration in a two component alloy? My problem: Uranium decays to thorium. The thorium isotopes it decays to typically have pretty short half lives. During casting, it is well known that thorium fractionates to the slag, crucible...

Hi, In an enclosed system - of say Methane & water - in which the water column is sufficiently large to have significant pressure and some modest temperature difference due to gravity and geothermal effects, how would one calculate / predict the changing methane concentration (or partial...

Homework Statement An intrinsic semiconductor with a direct gap have valance band ##\epsilon_k = E_v-b|k|^2## and conduction band ##\epsilon_k = =E_c+a|k|^2##, with ##E_v=6.0##eV, ##E_c = 5.5eV##, ##a=5.0eV\cdot Å^2##, and ##b=3.0eV\cdot Å^2##. Calculate the chemical potential ##\mu## and the...

I am computing limit of detection of zinc of an electrolyte. Using standard additions method, I have obtained positive x intercepts for 6/8 samples all very close to zero. Positive x-intercepts imply final concentration values to be negative. if x-intercept taken to be zero, the concentration...

I have a question regarding a problem in chemistry. I ultimately solved it, but I wanted to know if the problem itself could be represented as a differential equation, and if the solution I found is the solution to that equation. The explanation is a little long, but I don't think I can make it...

Some people want to improve their powers of concentration, and even help others do the same. Perhaps some members of this forum have found useful techniques they would like to share. One thing that fascinates me is how the subconscious comes to the rescue at times. For example, I make a mistake...

Homework Statement Determine electron concentration for both Helium and Nitrogen as a function of pressure at 300K. This is from preliminary task for Energy loss of alpha particles in gases laboratories. It's too late to submit this, I'd just like to understand. Can post more info from the lab...